Note: Descriptions are shown in the official language in which they were submitted.
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
ENZYME COMPOSITIONS AND METHODS
. FOR CONTACT LENS CLEANING
Backqround of the ~nvention
The present invention relates to enzyme-containing
compositions and methods employing such enzyme- containing
compositions ~or contact lens cleaning. More
particularly, the invention relates to such enzyme-
containing compositions and to contact lens cleaningmethods employing enzyme-containing compositions which
provide for deactivating the enzyme after the contact lens
has been effectively enzymatically cleaned.
The growth of the contact lens industry has led to a
dramatic increase in the number of contact lens care
systems. One goal of the lens care industry has been to
simplify lens care systems while, at the same time,
providing for effective, high quality care, and safe and
comfortable wearing of the treated contact lenses.
In the normal course of wearing contact lenses,
debris, such as tear film and proteinaceous, oily,
sebaceous and related organic matter, has a tendency to
deposit and build up on the lens surface. As part of the
routine care of a contact lens, it should be cleaned to
remove this debris. If this debris is not removed, the
lens can become uncomfortable to wear and may even damage
the eye.
One approach to removing debris buildup from contact
lenses has been to subject the debris laden lenses to
enzymatic action. For example, Karageozian U.S. Patent
3,910,296 discloses the use of proteases for cleaning
contact lenses.
Ogata U.S. Patent 4,285,738 discloses the us-e of
compositions comprising u~ea and/or an acid salt of
guanidine, a reducing agent and a proteolytic enzyme, with
or without additionally heating, to clean contact lenses.
Proteolytic enzymes disclosed include papain, trypsin,
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WO95/00621 PCT~S94/06840
21 65074 ~
alpha-chymotrypsin, pronase p from S. griseus and
. ~ ~
proteinase from B. subtilis.
Anderson U.S. Patent 4,521,254 discloses methods and
compositions for cleaning contact lenses comprising an
endopeptidase such as bromelain and a carboxy peptidase
enzyme.
Schaefer U.S. Patent 4,609,493 discloses contact lens
cleaning compositions containing a proteolytic enzyme, an
anionic surfactant, a calcium chelating agent and urea.
The calcium chelating agent is disclosed as a principal
lens cleaning ingredient which does not significantly
decrease the activity of the enzyme. Preferred enzymes
are pancreatin and papain. -
Ogunbiyi U.S. Patent 4,614,549 discloses methods for
cleaning and thermally disinfecting contact lenses and
deactivating the enzymes used for this process through the
use of proteolytic enzymes in aqueous solutions which are
heated to an elevated temperature between 60 C and 100
C.
Ogunbiyi U.S. ~atent 4,614,549 discloses the use o~
activator-free microbial-derived proteolytic enzymes as
well as chelating agents such as salts of ethylene diamine
tetraacetate (EDTA) to bind metal ions in solution such as
calcium, which might otherwise react with lens protein and
collect on lens surfaces.
Ogunbiyi U.S. Patent 4,690,773 discloses methods for
cleaning contact lenses with an activator-free enzyme
solution comprising an aqueous solution containing a
protease derived from a Bacillus, Streptomyces or
Aspergillus microorganism. The microbial proteases
disclosed require no additional activators or stabilizers
and are not inhibited when in the presence of a chelating
agent. This patent discloses that enzymes which are
inhibited by chelating agents are generally unsatisfactory
for use with contact lenses. Also, this patent discloses
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wo 95/006al 2 1 6 5 0 7 4 PCT~S94/06840
that proteases should be active at a pH range of from 5 to
.
8.5
Huth et al U.S Patent Reissue 32,672 discloses
methods for simultaneous cleaning and disinfecting of
contact lenses using a disinfecting amount of peroxide and
peroxide-active enzymes. Neutral, acidic or alkaline
enzymes, as well as metallo-proteases, may be used
Mowrey-McKee U.S. Patent 5,096,607 discloses methods
for simultaneously cleaning and disinfecting contact
lenses using polymeric quaternary ammonium salts or
biguanides, a proteolytic enzyme and an agueous system
wherein the osmotic value is adjusted to a level which
does not substantially inhibit the activity of the
antimicrobial agent. This patent discloses that
additional components, such as chelating and/or
sequestering agents, may be added to or incorporated into
the enzyme which do not substantially decrease the
activity of the enzyme.
None of the aforementioned patents discloses me~hods
or compositions to ~nactivate cleaning enzymes via ionic
regulators in the absence of heat input.
An important concern relating to the enzymatic
cleaning systems currently being employed is the need to
remove the enzyme from the lens prior to placing the
cleaned lens in the eye. Placing a lens contaminated with
cleaning enzyme into the eye may be potentially
detrimental to the eye. This potential problem, if any,
is avoided currently by rinsing the contact lens free of
cleaning enzyme prior to placing the cleaned lens in the
eye. However, this rinsing step may adversely impact user
compliance since the user may consider such rinsing
unnecessary and, as a result, place active enzyme in the
eye. Additionally, in some instances, rinsing the contact
lens free of cleaning enzyme may be insufficient to
eliminate discomfort, irritation and detrimental ocular
SUBSTITUTE SHEET (RULE 26)
WO95/00621 PCT~S94/06840
21 65074 ~
effects due to lens-bound active enzyme which may desorb
or elute from the contact lens into the eye
An additional concern relating to the enzymatic
cleaning systems currently employed is that the lenses are
often rubbed between the thumb and forefinger or in the
palm of the hand, to remove the loosely adherent debris
still r~m~in~ng on the contact lens. Rubbing lenses often
causes tearing and thus loss of the lens. The amount of
debris rem~in;ng on the lenses is related to the cleaning
efficiency of the enzyme composition which, in turn, is
related to the concentration of enzyme employed. Current
enzyme compositions must utilize lower concentrations of
enzyme to avoid possible ocular surface damage if they are
placed into the eyes. It would be advantageous to provide
a system in which the lens is effectively cleaned without
such rubbing.
Summary of the Invention
New contact lens treatment systems have been
discovered. The present systems in~olve the use of
enzymes, preferably/faster and/or more efficient enzymes
and enzyme-con~;n;ng formulations, to clean contact
lenses while reducing, and even eliminating, the risks of
rubbing lenses and also placing active cleaning enzyme in
the eye. Further, the present systems may not require
rubbing and/or rinsing the cleaned contact lens prior to
placing the lens in the eye. In other words, in one
embodiment the cleaned contact lens is suitable to be
taken directly from the enzyme-containing liquid medium,
in which the enzymatic cleaning takes place, and placed in
the eye for safe and comfortable wear without risking
damaging the lens or placing a damaging amount of active
cleaning enzyme in the eye. The present invention takes
advantage of activity regulating components which control
the level of activity of various contact lens cleaning
enzymes. Thus, by controlling the activity regulating
SUBSTITUTE SHEET (RULE 26~
WO95/00621 2 ~ 6 5 0 7 4 PCT~S94/06840
components to which the enzymes are exposedi effective
enzymatic cleaning of the contact lens can be obtained,
r and then the enzymes can be effectively deactivated so as
to render the enzymes inactive, and preferably
5 substantially innocuous, for example, in the environment
present in the eye. The present systems are relatively
easy to manufacture, often include conventional and
commercially available components, and are very easy to
use, providing for good user compliance. In addition, the
10 present systems can include components effective to
disinfect contact lenses, for example, while the lenses
are being enzymatically cleaned. Such "one step" systems
for the cleaning and disinfecting of contact lenses are
not only effective, but also are very convenient and easy
15 to use, thus further ~nh~ncing user compliance.
In one broad aspect of the present invention,
compositions useful for cleaning contact lenses are
provided and comprise an enzyme component and an activity
regulating component. The enzyme component is present in
20 an amount effectivç' when released in a liquid medium to
remove debris from a contact lens located in the liquid
medium. The activity regulating component, preferably an
ionic and/or inorganic activity regulating component
and/or a metal chelating activity regulating component, is
25 present in an amount effective when released in the liquid
medium to deactivate the enzyme component located in the
liquid medium. In one embodiment, such compositions may
be, and preferably are, structured so that the enzyme
component is released in the liquid medium a period of
30 time before the activity regulating component is released
in the liquid-medium. This period of time is sufficient
to allow the enzymatic component to effectively remove
- debris, preferably to completely remove at least one type
of debris, from a contact lens which is introduced into
35 the liquid medium before or at the same time the enzyme
....
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WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
com~ent ;~ released in the liquid medium. Alternately,
the enzyme component may be released in the liquid medium
at about the same time as the acti~ity regulating
component. In this embodiment, the interaction/reaction
between the activity regula~ing component and the enzyme
component can take place while the enzyme component is
removing debris from the contact lens and is slow enough
to allow sufficient lens cleaning, debris removal, to take
place prior to or simultaneously with enzyme component
deactivation.
Using the compositions as described herein, one can
remove the cleaned contact lens from the liquid medium
after the activity regulating component has deactivated
the enzyme component, and safely place the contact lens in
the eye with or without intermediate rubbing and/or
rinsing steps. More potent enzyme components and/or
greater amounts of enzyme components than are
conventionally employed to clean a contact lens can be
satisfactorily and safely used in accordance with the
present invention, /thereby Pl;~;n~ting the need for a
separate contact lens rubbing step. Amounts of enzyme
component equal to at least about 200~ or at least about
400~ or more (based on enzymatic activity) of the amount
of enzyme component conventionally employed may be used.
25The present methods for cleaning contact lenses can
employ compositions as described herein. For example, in
one embodiment such methods comprise introducing a contact
lens into a liquid medium, and introducing a composition,
as described above, into the liquid medium. The contact
lens is preferabl~ introduced into the liquid medium at
substantially the same time as the composition is
introduced into the liquid medium. The present methods
provide effectively cleaned contact lenses which may be
placed in the eye directly from the liquid medium for safe
and comfortable wear.
SUBSTITUTE SHEET (RULE 26)
WO9~/00621 PCT~S94l068q0
In one very useful embodiment, the liquid medium
includes a disinfectant component in an amount effective
to disinfect the contact lens located in the liquid
medium. In this embodiment, the contact lens is both
cleaned and disinfected Such l'one-step~ cleaning and
disinfecting systems are effective and easy for the
contact lens wearer to use.
Detailed Description of the Invention
The present invention can be used with all contact
lenses such as conventional hard, soft, rigid gas
permeable, and silicone lenses. The invention is
preferably employed with soft lenses, such as those
commonly referred to as hydrogel lenses prepared from
monomers, such as hydroxyethylmethacrylate,
vinylpyrrolidone, glycerylmethacrylate, methacrylic acid
or acid esters and the like. Hydrogel lenses typically
absorb significant amounts of water, such as in the range
of about 38 to about 80 percent by weight or more.
The present invention generally employs an effective
amount of enzyme component to remove debris from a contact
lens. Among the types of debris that form on a contact
lens during normal use are protein-based debris, mucin-
based debris, lipid-based debris and carbohydrate-based
debris. One or more types of debris may be present on a
2~ single contact lens.
The specific amount of enzyme component employed
depends on several factors including, for example, the
particular enzyme or enzymes employed, the activity of the
enzyme or enzymes, the purity of the enzyme, the amount
and type of debris deposited on the lens, the desired
soaking period, the nature and concentration of the
disinfecting agent if any, the specific type of lenses, as
well as other well known factors.
~The liquid medium preferably should contain
3~ sufficient enzyme to provide between about 0.0001 to 0.5
-
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
Anson units of activity per single lens .treatment, more
preferably between 0.0010 and 0.05, and still more
preferably between 0.0020 and 0.020, Anson units per
single lens treatment, in 1 to 10 ml of liquid medium.
The precise amount of enzyme on a weight per unit volume
of liquid medium basis depends, for example, on the purity
of the enzyme and may need to be finally determined on a
lot-by-lot basis.
The activity regulating component is present in an
amount effective when released in the liquid medium
containing the enzyme component to deactivate the enzyme
component. Of course, the activity regulating component
should be chosen to deactivate the specific enzyme
component being employed. One activity regulating
component may be effective against one or more of certain
enzymes while not being effective against other enzymes.
Thus, it is important that the proper enzyme
component/activity regulating component couple be chosen.
In addition, the activity regulating component should be
chosen so as to hav~ no substantial detrimental effect on
the lens being treated or on the eyes of the wearer of the
treated contact lens.
Various specific classes of enzyme component/activity
regulating component couples are descri~ed in detail
herein. However, it should be noted that the scope of the
present invention is such as to provide, in general, for
the deactivation of a contact lens cleaning enzyme
component in the liquid medium containing the contact lens
during and/or after contact lens cleaning. In this
manner, the cleaned contact lens can be removed from this
deactivated enzyme-containing liquid medium and placed
directly in the eye of the contact lens wearer for safe
and comfortable wear. Little or no risk of lens damage
from rubbing or of ocular surface damage from the active
enzyme component exists. The scope of the present
SUBSTITUTE SltEET (RULE 26)
WO95/00621 - PCT~S94/06840
~ 2165074
invention also includes enzyme components which can be
inactivated by ~he activity regulating components present
in the eye. For example, an acid-acting protease active
only at a pH less than about 6 may be employed together
5 with a disinfecting agent in a weakly acid buffered
solution to simultaneously clean and disinfect contact
len~es. A~ter such cleaning and disinfecting, the lenses
may be placec directly into the eyes without rinsing the
acid-acting protease ~rom the lenses. In this embodiment,
the naturally occurring pH buffers in the eye quickly
raise the pH to a value above 6, which decrease in acidity
inactivates the acid-acting.protease.
In one embodiment, the enzyme component/activity
regulating component couple is chosen so that the activity
regulating component comprises an ionic and/or inorganic
component and/or a metal chelating component in an amount
e~fective to inactivate the enzyme component.
In one embodiment, the enzyme component/ionic and/or
inorganic activity regulating component (IIARC) couple is
chosen so that the/enzyme component comprises an acid-
acting enzyme and the IIARC, preferably comprising
hydroxyl ions, is e~fective to change, for example,
reduce, the acidity of a liquid medium containing the
acid-acting enzyme to a level at which the acid acting
enzyme is substantially inactive. This "inactive" level
of acidity is preferably in the pH range o~ about 6.0 to
about 8.5, which approximately corresponds to the
physiological pH range ~or humans. Thus, after the acid-
acting enzyme component has been deactivated, the cleaned
contact lens can be removed ~rom the liquid medium, which
now has a physiologically acceptable pH, and placed
directly into the eye for safe and comfortable ~ear.
- ~lternatively, the cleaned contact lens, including
residual acid-acting enzyme component-containing liquid
medium may be placed directly into the eye, provided that
SUBSTITUTE SHEET (RULE 26)
WO95/00621 PCT~S94/06840
21 65074 ~
the liquid medium is weakly acid buffered. In this
instance, the naturally occurring pH bu~fers in the eye
quickly re-adju~t the pH to a level above about 6.0 and,
thus, substantially inactivate the acid-acting enzyme.
Various acid-acting enzymes may be employed.
Preferably, the enzyme component is effective at a pH in
the range of about 2 to about 5, more preferably about 3
to about 5. Specific examples of acid-acting enzymes
which may be employed in the present invention include
pepsin, gastricsin, chymosin (rennin), cathepsin D,
genetically engineered enzymes, such as subtilisins, with
acid pH activity profiles, rhizopus chinensis acid
protease, protease B isolated from Scvtalidium liqnicolum
(ATCC 24568) and Lentinus edodes TMI-563, acid proteases
isolated from Ganoderna lucidum IFO49~2, Pleurotus
cornucoPia, Pleurotus astreatus IFO 7051, Flammulina
veluti~es IFO 7046 and Lintinus edodes IFO 4902, acid
proteases isolated from cells and in the culture medium of
Sulfolobus acidocaldarius (thermopsin), Sulfolobus
solataricus and ThermoPlasma acidophilum, penicillium
roqueforti acid protease, fungal acid proteases such a
penicillopepsin from Penicillium janthinellum,
aspergillopeptidase A from AsPerqillus saitoi, endothia
acid protease from Endothia parasitin, mucor renn~n.~ from
Mucor michei, and the like and mixtures thereof.
If the enzyme component is acid acting, an acidity
adjusting component is chosen to pro~ide the activity
regulating component, for example, hydroxyl ions. The
acidity adjusting component may be selected, for example,
from bases (basic components), basic salts, basic buffers,
and mixtures thereof, more preferably from basic buffers
and mixtures thereof. Specific examples of useful acidity
adjusting components include those which are
ophthalmically acceptable at physiologically compatible
pHs. A material is ophthalmically acceptable if it can be
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
placed in the eye without causing any significant
detrimental e~fect on the eye Examples of useful acidity
adjusting components include alkali metal hydroxides,
alkali metal carbonates, alkaline metal bicarbonates,
alkaline earth metal hydroxides, alkaline earth metal
carbonates, alkaline earth metal bicarbonates, borates,
sodium and potassium phosphates, amino acid buffers and
the like and mixtures thereof. The amount of acidity
adjusting component used in the present invention is such
as to provide sufficient activity regulating component to
render the acidity of the liquid medium sufficiently
reduced so that the acid-acting enzyme component is
substantially inactive.
In one useful embodiment, the acid-acting enzyme
component/IIARC couple is included with an acidity
increasing component in an amount effective when released
in the liquid medium to increase the acidity of the liquid
medium to a level at which the acid-acting enzyme is
active. The above-noted couple and acidity increasing
component are preferably present in a composition which is
structured to release the acidity increasing component
before or at about the same time the acid-acting enzyme is
released in the liquid medium. In this embodiment, the
liquid medium, which may have a pH in the range of about
6.5 to about 8, is su~jected to the action of the acidity
increasing component, which increases the acidity of the
liquid medium, preferably to a pH in the range of about 2
or about 3 to about 5. The acid-acting enzyme component
then effectively cleans the contact lens. After this
cleaning has occurred, the acidity adjusting component is
released in the liquid medium to provide activity
regulating component to reduce the acidity of the liquid
medium, preferably to a pH in the range of about 6 to
about 8.5. In this manner, the acidity of the liquid
medium is controlled to effectively clean the contact lens
SUBSTITUTE S~tEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
and then to effectively inactivate or deactivate the acid-
acting enzyme component
Examples of useful acidity increasing components
include acids (acidic components), acid salts, acidic
S buffers and mixtures thereo~, preferably acidic buffers
and mixtures thereof. Examples of useful acidic
increasing components include hydrochloric acid, boric
acid, tartaric acid, citric acid and mixtures thereof.
The amount of acidity increasing component employed
in the present invention is such as to increase the
acidity of the liquid medium being employed to a level at
which the enzyme component is active. The specific
amounts of acidity increasing component vary depending
upon the specific acidity increasing component employed,
the amount and composition of the liquid medium being
employed and the like factors.
In a further specific embodiment, the enzyme
component/activity regulating component couple is chosen
so that the enzyme component is sensitive to being
deactivated by a /metal component and the activity
regulating component comprises this metal component. In
this embodiment, the presence of the metal component is
often effective to permanently or temporarily deactivate
the enzyme component. Whether or not the deactivation can
be reversed (or is temporary) depends, among other
factors, on the specific enzyme or enzymes being employed.
In the case of enzymes which are deactivated by ionic
metal components, one can easiiy determine if this
deactivation is permanent, simply by testing for enzymatic
activity after the enzyme has been removed from the ionic
metal component. ~hus, if the deactivated (inactive)
enzyme component s removed from the liquid medium
containing the ionic metal component and placed into a
medium cont~;n;ng a suf~icient amount of a metal chelating
agent or component, such as ethylene diamine tetraacetic
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/068~0
.
13
acid or its ophthalmically acceptable salts (referred to
collectively as EDTA), the enzyme component may again
become active. Of course, if insufficient metal chelating
agent is employed, the enzyme component remains inactive.
Since many liquid media used to clean, or otherwise
treat, contact lenses include some amount of metal
chelating agent, it may be important to use an additional
amount of metal component and/or to wait an additional
amount of time in order to achieve satisfactory enzyme
component deactivation in such liquid media. In addition,
by selectively choosing the type and amount of the ënzyme
component, metal component and metal chelating agent, one
can obtain both effective contact lens cleaning and
effective enzyme component deactivation with or without a
delayed release component.
In a particularly useful embodiment, the metal
component-sensitive enzyme component is genetically
engineered, for example, using conventional genetic
engineering, such as recombinant DNA, techniques, to be
sensitive to bei~g deactivated by the ionic metal
component. Many enzymes can be genetically modified to be
sensitive to metal component deactivation. Examples of
such enzymes include trypsin,subtilisin, chymotrypsin and
the like and mixtures thereof.
The metal component may be chosen from a wide variety
of materials, provided that such component effectively
aeactivates the enzyme component being employed.
Particularly useful examples of metal components include
alkaline earth metal components, transition metal
3~ components, such as copper components, iron (e.g., Fe'3)
components, zinc components, magnesium components and the
like, and mixtures thereof. Zinc components are
particularly useful.
The amount of metal component used should be such as
to render the enzyme component inactive enough such that
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
~he enzyme-con~aining solution does not harm the eye. The
metal component is prefera~ly present in a form which is
soluble after being released into the liquid medium. Some
excess of metal component may be usefully employed to
facilitate rendering the metal component-sensitive enzyme
component inactive. However, large excesses of metal
component should be avoided as being wasteful and as being
potentiall~ damaging, for example, to the contact lens
being treated or to the wearer of the treated contact
lens. The metal component should be chosen to be
compatible with the present system. Preferably, the metal
component is ophthalmically acceptable at. the
concentrations used in the present invention.
In another specific embodiment, the enzyme component
is activated by the presence of a metal. Thus, such a
metal-activated enzyme component is present in an amount
effective when released in a liquid medium to remove
debris from a contact lens located in the liquid medium.
The activity regulating component, for example, a metal
chelating agent eff~ctive to chelate or otherwise render
ineffective the metal associated with the metal-activated
enzyme component, is present in an amount effective to
deactivate, preferably substantially completely
deactivate, the metal-activated enzyme component located
in the liquid medium over a period of time. This period
of time is sufficient to allow the metal-activated enzyme
component to effectively remove debris from a contact lens
which is introduced into the liquid medium before or at
the same time the metal-activated enzyme is released in
the liquid medium.
Although any suitable activity regulating component
may be employed which is capable of deactivating the
metal-activated enzyme component, it is pre~erred that the
activity regulating component comprise a metal chelating
component effective over the period o~ time noted above to
SUBSTITUTE SHEET (RULE 26)
W095/00621 2 1 6 5 0 7 4 PCT~Sg4/06840
chelate, for example, complex and/or o~herwise interact
with and thereby render permanently or temporarily
ineffective, metal ions, such as the metal associated
with, for example, the metal needed to activate, the
metal-activated enzyme component. Examples of particularly
useful metal-activated enzyme components are those
selected from alkaline earth metal-activated proteases,
preferably calcium-activated proteases.
Examples of metal chelating agents or components
which are useful in the present invention as activity
regulating components include EDTA. Other ophthalmically
acceptable metal chelating components or metal
sequestering components, such as certain polyvinyl
alcohols, may be employed in the present invention,
provided that such other components function as activity
regulating components as described herein. Metal
chelating compone~ts may be employed to slow or,
preferably, to control the release of the metal activity
regulating components in the liquid medium
- 20 The metal chel~ing activity regulating component may
be released in the liquid medium at the same time the
metal-activated enzyme component is released. In this
instance, the deactivating (rendering ineffective) o~ the
metal-activated enzyme component is su~iciently slow so
that the enzyme component r~m~;n.~ active and e~fective to
remove debris from a contact lens for a period of time.
Eventually, a sufficient amount of the metal associated
with the metal-activated enzyme component is deactivated,
preferably substantially completely deactivated.
In another embodiment, the metal-activated enzyme may
be present in the liquid medium into which is introduced
the contact lens to be cleaned. The activity regulating
component can be introduced into this liquid medium at the
same time or after the contact lens is introduced into the
liquid medium. The acti~ity regulating component does,
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
over time, interact or o~herwise affect the metal
associated with the metal-activated enzyme component to
deactivate, preferably substantially completely
deactivate,.the enzyme component.
The amount o~ activity regulating component used in
accordance with the present invention to deactivate a
metal-activated enzyme component varies widely and
depends, for example, on the specific type and amount of
metal-activated enzyme component being employed, on the
specific activity regulating component being employed, on
the amount of time during which the metal-activated enzyme
component is to be deactivated after release of the
activity regulating component, and the like ~a-ctors.
Excessive amounts of activity regulating components should
be avoided since this i8 wasteful and unnecessary and may
have detrimental effects, for example, on the wearer of
the cleaned contact lens. The amount of acti~ity
regulating component employed is preferably no more than
about 200~ or about 300~ of that amount needed to
completely deacti~a~e the metal-activated enzyme component
present in the liquid medium.
The enzyme component may be employed in liquid or
solid form. The enzyme component may be provided in a
solid form such as tablets, pills, granules and the like,
which is introduced into a liquid medium.
Additional components may be added to or incorporated
into the enzyme component-cont~;ning solid and/or the
liquid medium. For example, components such as
effervescing agents, stabilizers, buffering agents,
chelating and/or sequestering agents, coloring agents or
indicators, tonicity adjusting agents, surfactants and the
like can be employed. In addition, binders, lubricants,
carriers, and other excipiPnts normally used in prod~cing
tablets may be used when enzyme component-containing
tablets are employed.
SUBSTITUTE SI~EET (RULE 26)
- - -
W0~5/00621 = 2 1 6 5 0 7 4 PCT~S94/OG840
.
17
Effervescing agents are typically employed when the
enzyme component is provided in solid form Examples of
suitable effervescing agents include tartaric or citric
acid used in combination with a suitable alkali metal salt
5 such as sodium carbonate.
Examples of suitable buffering agents which may be
incorporated into an enzyme component-containing tablet or
the liquid medium include alkali metal salts such as
potassium or sodium carbonates, acetates, borates,
phosphates, citrates and hydroxides, and weak acids such
as acetic acid and boric acid. Preferred buffering agents
are alkali metal borates such as sodium borate and
potassium borate. Additionally, other pH adjusting agents
may be employed, such as inorganic acids. For example,
hydrogen chloride may be employed in concentrations
suitable for ophth~1~;c uses. Generally, buffering agents
are present in amounts from about 0.01 to about 2.5~ (w/v)
and preferably, from about 0.2 to about 1.5~ (w/~), of the
liquid medium.
Examples of preferred metal chelating components
include EDTA which is normally employed in amounts rom
about 0.010 to about 2.0~ (w/v). Other metal chelating (or
sequestering) components such as certain polyvinyl
alcohols can also be employed. Usage of metal (metal ion)
chelating components should take under consideration the
possible presence o~ a metal component, for example, metal
ions, which may activate the enzyme component or which may
inactivate the enzyme component.
Any suitable colorant component and/or indicator
component may be included in the present compositions, for
exa~ple, to indicate the presence and/or the absence of
oxidative disinfectants, such as, hydrogen peroxide. A
particula~ly useful indicator component is cyano
cobalamine. Of course, other conventional colorant
components/indicator components may be employed.
SUBSTITUTE SltEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
18
The tonicity adjusting agent which may be-a component
of the l-iquid medium and may optionally be incorporated
into an enzyme component-containing tablet is employed to
adjust the osmotic value of the liquid medium.
Suitable surfactants can be either cationic, anionic,
nonionic or amphoteric. Preferred surfactants are neutral
or nonionic surfactants which may be present in amounts up
to 5~ (w/v). Examples of suitable surfactants include
polyethylene glycol esters of fatty acids,
polyoxypropylene ethers of C12-Cl~ alkanes and
polyoxyethylene, polyoxypropylene block copolymers of
ethylene diamine (e.e., poloxamine).
The binders and lubricants for enzyme tableting
purposes and other excipients normally used for producing
lS powders, tablets and the like, may be incorporated into
enzyme component-cont~;n;ng tablet formulations.
In a very useful embodiment, the acti~ity regulating
component is present in a delayed release form. Thus, the
activity regulating component may be introduced into the
liquid medium at t,h~ same time (and as part of the same
item or items which include the enzyme component) as the
enzyme component is introduced into the liquid medium.
However, the activity regulating component is released in
the liquid medium after the enzyme component is so
released. The release of the activity regulating
component is pre~erably delayed for a period of time
sufficient to allow the released enzyme component to
remove, more preferably completely remove, at least one
type of debris ~rom a contact lens present in the liquid
medium. Such sufficient time is preferably within about 6
hours, for example, in the range of about 1 minute to
about 6 hours, more preferably within about 4 hours, for
exa~ple, in the range of about 2 minutes to about 4 hours.
Although multi-layered (including core and coating
layering) tablets or pills are preferred, the delayed
SUBSTITUTE SHEET (RULE 26)
WO95100621 2 1 6 5 0 7 4 PCT~S94/06840
19
release forms of the present compositions can be present
in any other suitable item or items, such as masses of
powders, granules and the like. Delayed release
technology is well known in the art as exemplified by the
text Controlled Druq DeliverY, 2nd Ed., Joseph R. Robinson
& Vincent H.L. Lee, Eds., Marcel Dekker, Inc., New York,
1987.
Items which release their ingredients in a
sequential, time delayed manner are well known and can be
produced using conventional technology. Therefore, a
detailed description o~ such items and such production
technology is not presented.here.
In one useful embodiment, a direct compression is
made of the~ core tablet formulation using conventional
tableting equipment. A solution containing the delayed
release component is applied, e.g., sprayed, onto the core
tablet using conventional coating equipment, such as film
coating pans or fluid beds. Coating pan equipment is
available from Driam of West Germany, Thomas Engineering,
Vector corporation~/and Key Industries in the U.S. Fluid
bed equipment is available from Glatt Air Techniques,
Vector Corporation, and Aeromatic, as well as other
companies. Using a~Lo~riate coating parameters, which
are dependent on, for example, the speci~ic composition of
the delayed release component-cont~;n;ng solution, the
equipment used and core tablet size, an appropriate amount
of delayed release component is applied to the core tablet
that allows the desired delay release time.
Any suitable delayed release component or combination
of delayed release components may be employed, provided
that such component or components function as described
herein and have no substantial detrimental effect on
components used to treat the lens, on the lens being
treated and on the human wearing the treated lens. The
delayed release component is preferably at least
SUBSTITUTE SHEET (RULE 26)
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21 65074
partially, more prefera~ly completely, water soluble The
deIayed release component preferably comprises a major
amount of at least one polymeric material Examples of
useful delayed release components include, but are not
limited to, soluble cellulose ethers such as
methylcellulose, methylhydroxypropylcellulose,
methylhydroxyethyl-cellulose, hydroxypropylcellulose,
hydroxyethyl-celluloseandsodiumcarboxymethylcelluloses;
cellulose esters such as cellulose acetate phthalate and
hydroxypropylmethylcellulose phthalate; polymers derived
from at least one of acrylic acid, acrylic acid esters,
methacrylic acid and methacrylic acid esters such as
methacrylic acid-methyl methacrylate copolymer (for
example that sold by Rohm Pharma under the trademark
Eudragit L 100) and methacrylic acid-ethyl acrylate
copolymers (for example that sold by Rohm Pharma under the
trademark Eudragit L 30D); polymers derived from methyl
vinyl ether and maleic acid anhydride;
polyvinylpyrrolidone; polyvinyl alcohols and the like and
mixtures thereof. ~
The liquid meaium useful in practicing the present
invention is pre~erably aqueous-based. The liquid medium
can include a disinfectant component. Such disinfectant
component is present in a disinfecting amount, in
particular in an amount effective to disinfect a contact
lens.
A disinfecting amount of disinfectant component means
such amount as reduces the microbial burden to an
acceptable level within a reasonable soaking period, such
as four hours or less.
The disinfectant component may be oxidative or non-
oxidative. Particularly useful oxidative disinfectant
components are hydrogen peroxide or one or more other
peroxy-cont~; n; ng compounds, for example, one or more
other peroxides.
SUBSTITUTE SHEET (RULE 26)
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21
For hydrogen peroxide, a 0.5~ (w/v) concentration,
for example, in an aqueous liquid medium, is often
.. ... ..
effective as a disinfectant component. It is preferred to
use at least about l.o~ or about 2.0~ (w/v) hydrogen
peroxide which concentrations reduce the disinfecting time
over that of the 0.5~ (w/v) peroxide concentration. No
upper limit is placed on the amount of hydrogen peroxide
which can be used in this invention except as limited in
that the disinfectant component should have no substantial
detrimental effect on the contact lens being treated or on
the eye of the wearer of the treated contact lens. An
aqueous solution containing about 3~ (w/v) hydrogen
peroxide is very useful.
So far as other peroxides are concerned, they should
be used in effective disinfecting concentrations.
When an oxidative disinfectant is used in the present
invention, a reducing or neutralizing component in an
amount su~ficient to chemically reduce or neutralize
substantially all of the oxidative disinfectant, for
example, hydrogen p,eroxide, present is employed.
Such reducing or neutralizing components are
preferably incorporated into the enzyme component-
cont~;ning tablet. The reducing agent is generally any
non-toxic reducing agent. Reducing components include SH
(grc ~)-contA;n;ng water-soluble lower alcohols, organic
amines and salts therec , amino acids and di-or
tripeptides, e.g., cysteine hydrochloride ethyl ester,
glutathione, homocysteine, carbamoyl cysteine,
cysteinylglycine, 2-mercaptopropionic acid, 2-
mercaptopropionylglycine, 2-mercaptoethylamine
hydrochloride, cysteine, n-acetylcysteine, beta
mercaptoethanol, cysteine hydrochloride, dithiothreitol,
dithioerythritol, sodium bisulfate, sodium meta~isulfi~e,
thio urea, sulfites, pyrosulfites and dithionites such as
the alkali metal salts or alkaline earth metal salts of
SUBSTITUTE SHEET (RULE 26)
WO95/00~1 PCT~S94/068~
21 65074 ~
22
sulfurous acid, pyrosulfurous acid and dithionious acid,
e.g., lithium, sodium, calcium and magnesium salts and
mixtures thereof. The thiols are preferred, with N-
acetylcysteine being particularly useful.
In general, the reducing component is used in amounts
in the range of about 0.5~ to about 10~ (w/v) of the
liquid medium.
In one embodiment, all or a portion of the reducing
component is replaced by a peroxidase enzyme component, in
particular catalase, which acts to catalyze the
neutralization or decomposition of the oxidative
disinfectant component, such as hydrogen peroxide. Such
peroxidase enzyme component is included, for example, in
the enzyme component-containing core tablet, in an amount
effective to, together with the reducing component , if
any, destroy or cause the destruction of all the oxidative
disinfectant component present in the liquid medium. Some
excess peroxidase enzyme component may be advantageously
used to increase the rate at which the oxidative
disinfectant compo~ent is destroyed.
As used herein, non-oxidative disinfectant
components are non-oxidative organic chemicals which
derive their antimicrobial activity through a chemical or
physiochemical interaction with the microbes or
microorganisms. Suitable non-oxidative disinfectant
components are those generally employed in ophthalmic
applications and include, bu~ are not limited to,
quaternary ammonium salts used in ophth~l~;c applications
such as polyt(dimethylimino)-2-butene-1,4-diyl chloride,
alpha- [4-tris(2-hydroxyethyl) ammonium-2-butenyl-w-
tris(2-hydroxyethyl) ammonium]-dichloride (chemical
registry number 75345-27-6, available under the trademark
poiyquaternium 1~ ~rom ONYX Corporation), benzalkoniUm
halides, and biguanides such as salts of alexidine,
alexidine-free base, salts of chlorhexidine, hexamethylene
SUBSTITUTE SHEET (RULE 26~
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
.
23
biguanides and their polymers, antimicrobial polypeptides,
and ~he like and mixtures thereof.
The salts of alexidine and chlorhexidine can be
either organic or inorganic and are typically disinfecting
gluconates, nitrates, acetates, phosphates, sulphates,
halides and the like. Generally, the hexamethylene
biguanide polymers, also referred to as polyaminopropyl
biguanide (PAPB), have molecular weights of up to about
100,000. Such compounds are known and are disclosed in
U.S. Patent No. 4,758,595.
Another class of disinfectant components which meet
the foregoing criteria when detoxified are compounds
having the following formula:
(A) R -~+ - R2OH
~30H
wherein R is an alkyl or alkenyl group having 12-20 car~on
atoms and preferably a myristyl or tallow group, i.e.,
composed of mixtures of -Cl~H28 and C1~H29 (myristyl) or -
Cl7H3~ and -Cl,H35 (tallow); and Rl, R2, and R3 are the same
or different and represent alkyl groups having 1-3 carbon
atoms. This disinfectant component should be used
together with a detoxifying amount of a non-toxic
component, preferably selected from water soluble
polyhydroxyethyl methacrylate, carboxymethylcellulose,
non-ionic surfactants such as polyoxyethylene sorbitan
fatty acid esters and polyexethylene ethers,
polyvinylpyrrolidone, polyvinyl alcohol,
hydroxypropylmethylcellulose, and the like and mixtures
thereof.
The amount of the detoxifying component which is used
in connection with a disinfectant componënt disinfecting
ol Fol~.ula A varies widely, ~or example, in the range of
about 0.0001 to about 2.0~, preferably about 0.04 to about
0.4~, (w/v) of the liquid medium.
SUBSTITUTE SHEET (RULE 26)
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24
Another class of disinfectant components are the
quaternary ammonium substituted polypeptides, such as
those which are based on a collagen hydrolysate of
relatively low molecular weight. A particularly useful
quaternary ammonium substituent is the lauryl trimethyl
ammonium chloride group. The quaternary ammonium
substituted polypeptides preferably have molecular weights
in the range of about 500 to about 5000. One specific
example is that sold under the trademark Croquat L by
Croda, Inc.
Yet another class of disinfectant components are the
ophthalmically acceptable quaternary ammonium polymers
selected from ionene polymers containing an oxyge~ atom
covalently bonded to two carbon atoms and mixtures
thereof. Such polymers are described in Dziabo et al U.S.
Patent 5,145,643 which is incorporated in its entirety by
reference herein.
A specific example i8 poly [o~yethylene
(dimethyliminlo) ethylene -(dimethyliminio) ethylene
dichloride], sold ~nder the trademark WSCP by Buckman
Laboratories, Inc.
Other disinfecting agents include dodecyl-dimethyl-
(2-phenoxyethyl)-ammonium bromide.
Examples of ophthal~;cally acceptable anions which
may be included in the ionic disinfectant components
useful in the present invention include chloride (Cl),
bromide, iodide, bisulfate, phosphate, acid phosphate,
nitrate, acetate, maleate, fumarate, oxalate, lactate,
tartrate, citrate, gluconate, saccharate, p-toluene
sulfonate and the like.
The nQn-oxidative disinfectant components useful in
the present invention are preferably present in the liquid
medium in concentrations iIl the range of about 0.00001~ to
about 0.01~ (w/v). The more preferred range for polyquads
3S (e.g;, poly-quaternium-1) and biguanides is 0.00005~ to
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~Sg4/06840
about 0.0015~ (w/v) and for quaternary ammonium
substituted polypeptides (e.g., Croquat L) and polymers
(e.g. WSCP) is in the range of about 0.003~ to 0.015~
(w/v) .
More preferably the agent is present in the working
solution at an ophthalmically safe concentration such that
the user can rinse the lens with the solution and
thereafter directly place the lens in the eye.
For purposes of the present invention an aqueous
solution containing about 0.00001~ to about 0.005~ (w/v)
of a non-oxidative disinfectant component may be used as
a multipurpose solution. That is, the solution (liquid
medium) can be used for disinfection; cleaning (together
with the enzyme component), storage and rinsing. Thus, by
using the methodology of the present invention, the user
only needs to have the enzyme component/deactivator
component couple, for example, in the form of a delayed
release tablet, and a single solution, the multi-p~rpose
solution noted above or a single multi-purpose solution
which contains a,n acid-acting protease which is
neutralized by tears or fluids in the eye. There is no
longer a need to rub and rinse the cleaned lens or to use
a separate saline solution.
During practice of this invention, the enzyme
component/deactivator component formulation is in a liquid
medium, typically about 1 to about 10 ml. The liquid
medium may be isotonic, hypotonic or hypertonic, and may
include an effective amount of a disinfectant component.
The contact lens to be treated i5 preferably
introduced into the liquid medium at the same time the
above-noted formulation is so introduced if the enzyme is
not already present in the liquid medium. The contact
lens/liquid medium contacting occurs at conditions
effective to obtain the desired beneficial contact lens
care result or results, for example, cleaning o~ the
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
26
contact lens or cleaning and disinfecting o~ the contact
lens I the liquid medium is aqueous-based, as is
preferred, contacting temperatures in the range of about
0 C to about 100 C are preferred, with temperatures in
-5 the range of about 10 C to about 60 C being more
preferred and temperatures in the range of about 15 C to
about 40 C being still more preferred. Contact
lens/liquid medium contacting at ambient temperature is
very convenient and useful. Typically, the cleaning
contacting takes less than about eight hours, with about
1 to about 6 hours being preferred.
Preferably, the lens is removed from the liquid
medium and placed directly into the eye without the need
for separate rubbing and rinsing steps. Alternately, the
lens can be rinsed with a buffered saline solution, or
with a liquid medium having the same composition as that
used above (without enzyme), prior to insertion into the
eye.
It is most convenient to formulate the enzyme
component, deactiva~or component and other dry components
as a powder or tablet structured for delayed or sequential
release of components, as described herein. The contact
lens may already be in the liquid medium when the enzyme
component/deactivator component is introduced.
The following non limiting examples illustrate
certain embodiments of the present invention.
SUBSTITUTE SHEET (RULE 26)
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27
EXAMP~E 1
A layered tablet is prepared using conventional
techniques and has the following composition:
Core
Crystalline catalase 520 activity units
Cyano cobalamine 0.085 mg
Polyethylene glycol 3350 1.05 mg
Sodium chloride 89.4 mg
Sodium phosphate dibasic 12.5 mg
(anhydrous)
Sodium phosphate 1.0 mg
monobasic monohydrate
Zinc sulfate 5.0 mg
Core Coatinq
Hydroxypropylmethylcellulose 5.0 mg
Outer LaYer
Subtilisin A 0.0075 Anson Units
This tablet is introduced into 10 ml of a
conventional aqueous solution cont~;n;ng 3~ (w/v) of
hydrogen peroxide. A debris laden contact lens is
introduced into the solution at the same time. Very
quickly, the Subtilisin A enzyme is released into the
solution and-effectively removes debris from the contact
lens. The hydrogen peroxide in the solution also
effectively disin~ects the contact lens. After about 40
minutes, the core is released in the solution. The
catalase in the core is effective to cause the destruction
of all the hydrogen peroxide in the solution. Zinc ions
formed from the zinc sulfate present in the core are
effective to substantially completely inactivate the
Subtilisin A.
SUBSTITUTE S~IEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
The cleaned and disinfected contact lens can be
removed from the solution and placed directly in the eye
for safe and comfortable wear.~ Alternately, the cleaned
and disinfected contact lens can be rinsed with a
conventional buffered saline solution before being placed
in the eye for safe and comortable wear.
EXAMPLE 2
A layered tablet is prepared using conventional
techniques and has the following composition:
Core
Conventional sugar-based filler(Di-Pac) 40 mg
Polyvinylpyrrolidone 4 mg
Polyethylene glycol 3350 4 mg
Zinc sulfate 1.8 mg
Core Coatinq
Hydroxypropylmethylcellulose 2 mg
Outer La~er
Subtilisin A .0017 Anson Units
The following solution is prepared:
Polyaminopropy,l~
biguanide, w/v.~ 0.0001
Disodium ethylene
diamine tetraacetate (EDTA), w/v~ 0.05
Sodium chloride, w/v~ 0.37
TRIS(l), w/v~ 1.2
Nonionic surfactant(2), w/v~ 0.025
Purified water, USP QS
(13 Trometh~m;ne, otherwise known as
2-amino-2-hydroxy methyl-1,3-propanediol
(2) A nonionic surfactant containing
oxyethylated tertiary octylphenol
formaldehyde polymer and sold under the
trademark Tyloxapol by Ruger.
H~drochloric acid is added to the soluticn to give a
pH of about 7.5.
The above-noted tablet and a debris laden contact
lens (in a lens holder) are introduced into 1.8 ml o~ the
SUBSTITUTE S~EET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~Sg4/06840
above-noted solution at the same time ~pon being
introduced into the solution, the Subtilisin A is quickly
A released in the solution and efectively removes debris
from the contact lens In addition, the contact lens is
5 being e~fectively disinfected by the solution. After
about 1 hour, the core is released in the solution. Note
that the final solution contains a molar concentration o
zinc sulfate which is well in excess, for example, on the
order of about 4 times, the molar concentration of
lO disodium ethylene diamine tetraacetate. This molar excess
of zinc sulfate insures that the solution in which the
zinc sulfate is released contains a sufficient amount of
free (unchelated) zinc ions to substantially inactivate
the Subtilisin A enzyme. Zinc ions formed from the zinc
15 sulfate present in the core are effective to substantially
inactivate the Subtilisin A. The contact lens is left in
the solution for an additional 3 hours to complete
disinfecting the lens.
The cleaned and disinfected contact lens can be
20 removed from the composition and placed directly in the
eye for safe and comfortable wear. Alternately, the
cleaned and disinfected contact lens can be rinsed with a
conventional buffered saline solution or the above
polyaminopropylbiguanide-cont~; n; ngsolutionbeforebeing
25 placed in the eye for safe and comfortable wear.
EXAMPLE 3
Tablets are prepared, using conventional techniques,
which have the following composition:
Conventional sugar-based filler(Di-Pac) 40.0 mg
Polyvinylpyrrolidone (Kollidon 30) 4.0 mg
Polyethylene glycol 3350 4.0 mg
Subtilisin A MG 1.5 1.3 mg*
*Equal to .0017 Anson units en~ymatic activity
per tablet.
SUBSTITllTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
Four (4) Subtilisin A enzyme solutions are prepared,
each utilizing one o~ the above tablets and 1 8 ml of the
polyaminopropyl biguanide-containingsolutiondescribed in
Example 2. Different amounts of ZnSO4 are added to three
S of the solutions at the same time as the enzyme tablet.
The four solutions include the following components:
Solution 1 Solution 2 Solution 3 Solution 4
1 Tablet 1 Tablet 1 Tablet 1 Tablet
1.8 ml solu. 1.8 ml solu. 1.8 ml solu. 1.8 ml solu.
0 mg ZnSO~ 0.90 mg ZnSO~ 1.8 mg ZnSO~ 4.5 mg ZnSO~
Thirty two (32) commercially available soft (55
water content) contact lenses are coated with heat-
denatured lysozyme for contact lens cleaning tests as per
the method in Huth et al U.S. Reissue 32,672, the
disclosure of which is incorporated in its entirety herein
by reference.
The lenses are then placed in the test solutions,
eight (8) lenses per test solution. The lenses are soaked
for 2, 4, 8 and 20' hours. For each time interval, two
lenses from each test solution are ~m; ne~ under a
microscope to determine the extent of protein removal.
The percent cleaning equals the percent of the surface not
covered by a protein film at 100 times magni~ication. The
test solutions are measured for their enzymatic activity
according to the Azocoll method, Tomarelli, R.M., et al,
J. Lab ~lin. Med., 34, 428 (1949).
The cleaning and enzyme inactivation results are
presented in Table 1.
SUBSTIME SHEET (RULE 26)
PCT~S94/068~
WO95/00621 2 1 6 5 0 7 4
31
T~BLE 1
Solution 1 Solution 2 Solu~ion 3 Solution q
Soaking`-ZnSO~(~/v~) 0 0.05 0.1 0.25
Time
5 15 min ~cleaning Not ~es~ed Not tested Not tested Not tested
~enzyme
in ac~ivation 0 11 34 67
2 hours ~cleaning o O o o
~enzyme
inactivation 0 27 36 82
4 ho~rs~cleaning 20 20 10 0
~enzyme
inactivation 0 75 No data 88
8 hours ~cleaning60-.~. 40 40 0
~enzyme
lS inactivationNot testedNot tes~cedNo~ tested Not tested
20 hours ~cleaning 100 90 50 0
~enzyme
inactivation Not tested Not tested No~ tested Not ~ested
The results show the following:
20 (l) Substantial cle~n;ng and enzyme inactivation can
be achieved simulta/neously. Solution 2 is 75~ inactive at
4 hours and yet demonstrates acceptable cleaning in
comparison to Solution l which does not contain any zinc
sulfate.
(2) Increasing concentrations of zinc sulfate result
in increasing inactivation of Subtilisin A in a shortened
time frame.
(3) Zinc sulfate can inactivate Subtilisin A in the
presence of EDTA. An amount of zinc sulfate equal to 0.2~
w/v~ (Solution 4) is sufficient to eliminate all cleaning
in Solution 4 which contains about 0.05 w/v~ EDTA.
SUBSTITUTE Sl IEET (RULE 26
wo 9S/OO~1 2 1 6 5 0 7 4 PCT~594/06840
EXAMPLE 4
A layered tablet is prepared using conventional
techniques and has the ~ollowing composition:
Core
Crystalline catalase 520 activity units
Cyano cobalamine 0.085 mg
Polyethylene glycol 1.05 mg
(mol. wt. 3350)
Sodium Chloride 89.4 mg
Sodium phosphate dibasic 12.5 mg
(anhydrous)
Sodium phosphate l.O mg
monobasic monohydrate
Core Coatinq
Hydroxypropylmethylcellulose 5.0 mg
Outer LaYer
Aspergillo peptidase A(l) 0.0075 Anson Units
(1) Acid protease derived from As~erqillus
saitoi. Other acid proteases, for example,
other fungal acid proteases, can be employed
instead. / Also, genetically engineered acid
acting ,enzymes having activities and
activity/pH profiles equivalent to
Aspergillo peptidase A can be used instead.
Routine experimentation can be employed to
determine if any particular acid acting
enzyme, is effective. For example, the
activity of an enzyme can be monitored at
various pH levels to determine the usefulness
of the enzyme in this embodiment.
This tablet is introduced into 10 ml o a
conventional aqueous solution cont~;n;ng 3~ (w/v) of
hydrogen peroxide. A debris laden contact lens is
introduced into the solution at the same time. Very
quickly the Aspergillo peptidase A enzyme is released in
the solution, which has a pH of'3.5, and effectively
removes debris from the contact lens. The hydrogen
peroxide'in the solution also effectively disinfects the
contact lens. After about 40 minutes, the core is
SUBSTITUTE SI~EET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
33
released in ~he solution. The pH of the solution is-
increased to 7Ø This change in the pH inactivates the
Aspergillo peptidase A enzyme The phosphate buffers in
the core tablet are released after the Aspergillo
peptidase A enzyme effectively cleans the contact lens.
The catalase in the core is effective to cause the
destruction of all the hydrogen peroxide in the solution.
The cleaned and disinfected contact lens can be
removed from the solution and placed directly in the eye
for safe and comfortable wear. Alternately, the cleaned
and disinfected contact lens can be rinsed with a
conventional buffered saline solution before being placed
in the eye for safe and comfortable wear.
EXAMPLE 5
The following solution is prepared:
Polyaminopropyl 0.0001
biguanide, w/v~
Disodium ethylene 0.05
diamine tetraacetate, w/v~
Sodium chlorid~ Sufficient to provide
a hypotonic solution
having an osmolality
less than about 290
mOsmol/kg
Penicillo pepsin 0.0012 Anson Units/ml
Buffer Sufficient to maintain
pH of solution at 4
Nonionic surfactant, (2~ 0.025
w/v~
Purified water, USP QS
(1) The buffer and/or amount of buffer should be
selected~to maintain the soluti-on weakly
buffered at a pH of 4. Such buffering should
have no substantial effect if small
(residual) amounts of the solution are placed
in another liquid medium, for example, in the
tear fluid on a human eye. Examples of useful
buffers include citric acid-disodium hydrogen
phosphate, acetic acid-sodium acetate, succinic
acid-sodium hydroxide and the like.
SUBSTITUTE S~IEET (RULE 26)
WO95/00621 , ~- PCT~S94/06840
21 65074 ~
(2) Same as the nonionic surfactant ~escribed in
Example 2.
A debris laden, soft (hydrogel) contact lens, in a
lens holder, is placed in 1.8 ml of the above-noted
solution. The acid protease (Penicillo pepsin)
effectively removes debris from the contact lens. In
addition, the contact lens is being effectively
disinfected by the solution. The configuration (size) of
the contact lens is maintained throughout this contacting.
That is, the low pH of the solution tends to de-swell the
hydrogel contact lens, while the hypotonicity of the
solution tends to swell the lens. The balance between the
low pH and hypotonicity of the solution acts to maintain
the water content of the hydrogel contact lens at
substantially its value prior to contacting with the
solution.
After at least 4 hours (or overnight), the cl~ne~
and disinfected contact lens is removed from the solution
and placed directly into the eye for safe and comfortable
wear. In placing the contact lens directly from the acid
solution into the eye, the lens very quickly, for exa~ple,
in about 1 to about 2 minutes, becomes stabilized at a
physiological pH of about 7 to 7.5. At this pH, the acid
2S protease, Penicillo pepsin, is inactivated and does not
harm the eye. This embo~im~nt of the present invention is
a very effective one step, one solution approach to
cleaning and disinfecting contact lenses.
One important feature of the present invention,
particularly when soft hydrogel contact lenses are being
treated, is a system which is balanced so as to
substantially maint-ain the initial configuration (size) of
the contact lens, that is to substantially maintain the
water content of the contact lens, throughout the
contacting. As noted above, in Example 5, this
deswelling/swelling balance can be achieved using a
hypotonic solution in combination with an acid pH. An
SUBSTITUTE SHEET (RULE 26)
WO95/00621 2 1 6 5 0 7 4 PCT~S94/06840
alternative for use in combination with an acid pH is to
employ one or more other solutes, such as osmolytes which
tend to swell the lens, thereby balancing or countering
the lens deswelling effect of the low pH.
S EXAMPLE 6
A tablet is prepared, using conventional techniques,
containing 0.0017 Anson Units of a calcium activated
neutral protease, such as thermolysin.
The tablet and a debris laden contact lens (in a lens
holder) are introduced into 1.8 ml of the solution
identified in Example 2. Quickly after being introduced
into this solut on, the calcium acti~ated neutral protease
is released in the solution and effectively removes debris
from the contact lenæ. In addition, the contact lens is
being effectively disinfected by the solution. Over time,
the disodium ethylene diamine tetraacetate in the solution
chelates an increasingly large amount of the calcium
associated with the enzyme. This chelating (or
complexing) effectively inactivates the enzyme. After
about 4 to about 8 ~ours, the contact lens is effectively
cleaned and disinfected, and the enzyme is substantially
inactivated.
The cleaned and disinfected lens can be removed from
the composition and placed directly in the eye for safe
and comfortable wear. Alternately, the cleaned and
disinfected contact lens can be rinsed with a conventional
buffered saline solution or a solution such as in Example
2 before being placed in the eye for safe and comfortable
wear.
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21 65074
36
EXAMPLE 7
A layered tablet is prepared-using conventional
techniques and has the following composition:
Core
Conventional sugar-based filler(Di-Pac) 40 mg
Polyvinylpyrrolidone 4 mg
Polyethylene glycol 3350 4 mg
Disodium ethylene diamine 2 mg
tetraacetate
Core Coatinq
Hydroxypropyl methylcellulose 2 mg
Outer LaYer
Calcium activated neutral 0.0017 Anson Units
protease
A solution is prepared similar to that described in
Example 2 except the solution contains no disodium
ethylene ~; ~m; ne tetraacetate.
The tablet and a debris laden contact lens (in a lens
holder) are introduced into 1.8 ml o~ the above-noted
solution at the sam,e~time. Quickly after being introduced
into the above-noted solution, the calcium activated
neutral protease is released in the solution and
effectively removes debris from the contact lens. In
addition, the contact lens is being effectively
disinfected by the solution. After about 1 hour, the core
is released in the solution. The disodium ethylene
~;~m;ne tetraacetate present in the core
is effective to chelate the calcium associated with the
calcium activated neutral protease to substantially
inactivate this enzyme. The contact lens is left in the
solution for an additional 3 hours to complete
disinfecting the lens.
The cleaned and disinfected contact lens can be
removed from the composition and placed directly in the
eye for safe and comfortable wear. Alternately, the
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.
cleaned and disinfected contact lens can be rinsed with a
conventional buffered saline solution or a solution such
as in Example 2 before being placed in the eye for safe
and comfortable wear.
While this invention has been described with respect
to various specific examples and embodiments, it is to be
understood that the invention is not limited thereto and
that it can be variously practiced within the scope of the
following claims.
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